Hello As you mentioned complaints .i can say u may have iron deficiency anaemia or may not . For that u need to do  blood test like complete blood  count . And iron profile . . Sometime this test can come within normal range . So we are doing this to rule out anemia . If this test are comes normal then u should focus on u lifestyle and diet . Mostly green vegetable and if u r non vegetarian u can have red meat and fish  .. milk products . And as you say your appetite and digestion is very low so then instead of having big meal divide in several small meal . And exercise as per you are capacity .... after blood test i will recommend to visit u r nearby general medicine  dr. and nutritional expert .